// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:meta/meta.dart';

import '../base/common.dart';
import '../base/io.dart';
import '../base/os.dart';
import '../base/process.dart';
import '../cache.dart';
import '../dart/pub.dart';
import '../globals.dart' as globals;
import '../persistent_tool_state.dart';
import '../runner/flutter_command.dart';
import '../version.dart';

// The official docs to install Flutter.
const String _flutterInstallDocs = 'https://flutter.dev/docs/get-started/install';

class UpgradeCommand extends FlutterCommand {
  UpgradeCommand({
    required bool verboseHelp,
    UpgradeCommandRunner? commandRunner,
  })
    : _commandRunner = commandRunner ?? UpgradeCommandRunner() {
    argParser
      ..addFlag(
        'force',
        abbr: 'f',
        help: 'Force upgrade the flutter branch, potentially discarding local changes.',
        negatable: false,
      )
      ..addFlag(
        'continue',
        hide: !verboseHelp,
        negatable: false,
        help: 'Trigger the second half of the upgrade flow. This should not be invoked '
              'manually. It is used re-entrantly by the standard upgrade command after '
              'the new version of Flutter is available, to hand off the upgrade process '
              'from the old version to the new version.',
      )
      ..addOption(
        'working-directory',
        hide: !verboseHelp,
        help: 'Override the upgrade working directory. '
              'This is only intended to enable integration testing of the tool itself.'
      )
      ..addFlag(
        'verify-only',
        help: 'Checks for any new flutter updates, without actually fetching them.',
        negatable: false,
      );
  }

  final UpgradeCommandRunner _commandRunner;

  @override
  final String name = 'upgrade';

  @override
  final String description = 'Upgrade your copy of Flutter.';

  @override
  final String category = FlutterCommandCategory.sdk;

  @override
  bool get shouldUpdateCache => false;

  @override
  Future<FlutterCommandResult> runCommand() {
    _commandRunner.workingDirectory = stringArg('working-directory') ?? Cache.flutterRoot!;
    return _commandRunner.runCommand(
      force: boolArg('force'),
      continueFlow: boolArg('continue'),
      testFlow: stringArg('working-directory') != null,
      gitTagVersion: GitTagVersion.determine(globals.processUtils),
      flutterVersion: stringArg('working-directory') == null
        ? globals.flutterVersion
        : FlutterVersion(workingDirectory: _commandRunner.workingDirectory),
      verifyOnly: boolArg('verify-only'),
    );
  }
}

@visibleForTesting
class UpgradeCommandRunner {

  String? workingDirectory;

  Future<FlutterCommandResult> runCommand({
    required bool force,
    required bool continueFlow,
    required bool testFlow,
    required GitTagVersion gitTagVersion,
    required FlutterVersion flutterVersion,
    required bool verifyOnly,
  }) async {
    if (!continueFlow) {
      await runCommandFirstHalf(
        force: force,
        gitTagVersion: gitTagVersion,
        flutterVersion: flutterVersion,
        testFlow: testFlow,
        verifyOnly: verifyOnly,
      );
    } else {
      await runCommandSecondHalf(flutterVersion);
    }
    return FlutterCommandResult.success();
  }

  Future<void> runCommandFirstHalf({
    required bool force,
    required GitTagVersion gitTagVersion,
    required FlutterVersion flutterVersion,
    required bool testFlow,
    required bool verifyOnly,
  }) async {
    final FlutterVersion upstreamVersion = await fetchLatestVersion(localVersion: flutterVersion);
    if (flutterVersion.frameworkRevision == upstreamVersion.frameworkRevision) {
      globals.printStatus('Flutter is already up to date on channel ${flutterVersion.channel}');
      globals.printStatus('$flutterVersion');
      return;
    } else if (verifyOnly) {
      globals.printStatus('A new version of Flutter is available on channel ${flutterVersion.channel}\n');
      globals.printStatus('The latest version: ${upstreamVersion.frameworkVersion} (revision ${upstreamVersion.frameworkRevisionShort})', emphasis: true);
      globals.printStatus('Your current version: ${flutterVersion.frameworkVersion} (revision ${flutterVersion.frameworkRevisionShort})\n');
      globals.printStatus('To upgrade now, run "flutter upgrade".');
      if (flutterVersion.channel == 'stable') {
        globals.printStatus('\nSee the announcement and release notes:');
        globals.printStatus('https://flutter.dev/docs/development/tools/sdk/release-notes');
      }
      return;
    }
    if (!force && gitTagVersion == const GitTagVersion.unknown()) {
      // If the commit is a recognized branch and not master,
      // explain that we are avoiding potential damage.
      if (flutterVersion.channel != 'master' && kOfficialChannels.contains(flutterVersion.channel)) {
        throwToolExit(
          'Unknown flutter tag. Abandoning upgrade to avoid destroying local '
          'changes. It is recommended to use git directly if not working on '
          'an official channel.'
        );
      // Otherwise explain that local changes can be lost.
      } else {
        throwToolExit(
          'Unknown flutter tag. Abandoning upgrade to avoid destroying local '
          'changes. If it is okay to remove local changes, then re-run this '
          'command with "--force".'
        );
      }
    }
    // If there are uncommitted changes we might be on the right commit but
    // we should still warn.
    if (!force && await hasUncommittedChanges()) {
      throwToolExit(
        'Your flutter checkout has local changes that would be erased by '
        'upgrading. If you want to keep these changes, it is recommended that '
        'you stash them via "git stash" or else commit the changes to a local '
        'branch. If it is okay to remove local changes, then re-run this '
        'command with "--force".'
      );
    }
    recordState(flutterVersion);
    globals.printStatus('Upgrading Flutter to ${upstreamVersion.frameworkVersion} from ${flutterVersion.frameworkVersion} in $workingDirectory...');
    await attemptReset(upstreamVersion.frameworkRevision);
    if (!testFlow) {
      await flutterUpgradeContinue();
    }
  }

  void recordState(FlutterVersion flutterVersion) {
    final Channel? channel = getChannelForName(flutterVersion.channel);
    if (channel == null) {
      return;
    }
    globals.persistentToolState!.updateLastActiveVersion(flutterVersion.frameworkRevision, channel);
  }

  Future<void> flutterUpgradeContinue() async {
    final int code = await globals.processUtils.stream(
      <String>[
        globals.fs.path.join('bin', 'flutter'),
        'upgrade',
        '--continue',
        '--no-version-check',
      ],
      workingDirectory: workingDirectory,
      allowReentrantFlutter: true,
      environment: Map<String, String>.of(globals.platform.environment),
    );
    if (code != 0) {
      throwToolExit(null, exitCode: code);
    }
  }

  // This method should only be called if the upgrade command is invoked
  // re-entrantly with the `--continue` flag
  Future<void> runCommandSecondHalf(FlutterVersion flutterVersion) async {
    // Make sure the welcome message re-display is delayed until the end.
    final PersistentToolState persistentToolState = globals.persistentToolState!;
    persistentToolState.setShouldRedisplayWelcomeMessage(false);
    await precacheArtifacts();
    await updatePackages(flutterVersion);
    await runDoctor();
    // Force the welcome message to re-display following the upgrade.
    persistentToolState.setShouldRedisplayWelcomeMessage(true);
  }

  Future<bool> hasUncommittedChanges() async {
    try {
      final RunResult result = await globals.processUtils.run(
        <String>['git', 'status', '-s'],
        throwOnError: true,
        workingDirectory: workingDirectory,
      );
      return result.stdout.trim().isNotEmpty;
    } on ProcessException catch (error) {
      throwToolExit(
        'The tool could not verify the status of the current flutter checkout. '
        'This might be due to git not being installed or an internal error. '
        'If it is okay to ignore potential local changes, then re-run this '
        'command with "--force".\n'
        'Error: $error.'
      );
    }
  }

  /// Checks if the Flutter git repository is tracking a standard remote.
  ///
  /// A "standard remote" is one having the same url as [globals.flutterGit].
  /// The upgrade process only supports standard remotes.
  ///
  /// Exits tool if the tracking remote is not standard.
  void verifyStandardRemote(FlutterVersion localVersion) {
    // If repositoryUrl of the local version is null, exit
    final String? repositoryUrl = localVersion.repositoryUrl;
    if (repositoryUrl == null) {
      throwToolExit(
        'Unable to upgrade Flutter: The tool could not determine the remote '
        'upstream which is being tracked by the SDK.\n'
        'Re-install Flutter by going to $_flutterInstallDocs.'
      );
    }

    // Strip `.git` suffix before comparing the remotes
    final String trackingUrl = stripDotGit(repositoryUrl);
    final String flutterGitUrl = stripDotGit(globals.flutterGit);

    // Exempt the official flutter git SSH remote from this check
    if (trackingUrl == 'git@github.com:flutter/flutter') {
      return;
    }

    if (trackingUrl != flutterGitUrl) {
      if (globals.platform.environment.containsKey('FLUTTER_GIT_URL')) {
        // If `FLUTTER_GIT_URL` is set, inform the user to either remove the
        // `FLUTTER_GIT_URL` environment variable or set it to the current
        // tracking remote to continue.
        throwToolExit(
          'Unable to upgrade Flutter: The Flutter SDK is tracking '
          '"${localVersion.repositoryUrl}" but "FLUTTER_GIT_URL" is set to '
          '"${globals.flutterGit}".\n'
          'Either remove "FLUTTER_GIT_URL" from the environment or set it to '
          '"${localVersion.repositoryUrl}", and retry. '
          'Alternatively, re-install Flutter by going to $_flutterInstallDocs.\n'
          'If this is intentional, it is recommended to use "git" directly to '
          'keep Flutter SDK up-to date.'
        );
      }
      // If `FLUTTER_GIT_URL` is unset, inform that the user has to set the
      // environment variable to continue.
      throwToolExit(
        'Unable to upgrade Flutter: The Flutter SDK is tracking a non-standard '
        'remote "${localVersion.repositoryUrl}".\n'
        'Set the environment variable "FLUTTER_GIT_URL" to '
        '"${localVersion.repositoryUrl}", and retry. '
        'Alternatively, re-install Flutter by going to $_flutterInstallDocs.\n'
        'If this is intentional, it is recommended to use "git" directly to '
        'keep Flutter SDK up-to date.'
      );
    }
  }

  // Strips ".git" suffix from a given string, preferably an url.
  // For example, changes 'https://github.com/flutter/flutter.git' to 'https://github.com/flutter/flutter'.
  // URLs without ".git" suffix will remain unaffected.
  String stripDotGit(String url) {
    final RegExp pattern = RegExp(r'(.*)(\.git)$');
    final RegExpMatch? match = pattern.firstMatch(url);
    if (match == null) {
      return url;
    }
    return match.group(1)!;
  }

  /// Returns the remote HEAD flutter version.
  ///
  /// Exits tool if HEAD isn't pointing to a branch, or there is no upstream.
  Future<FlutterVersion> fetchLatestVersion({
    required FlutterVersion localVersion,
  }) async {
    String revision;
    try {
      // Fetch upstream branch's commits and tags
      await globals.processUtils.run(
        <String>['git', 'fetch', '--tags'],
        throwOnError: true,
        workingDirectory: workingDirectory,
      );
      // '@{u}' means upstream HEAD
      final RunResult result = await globals.processUtils.run(
          <String>[ 'git', 'rev-parse', '--verify', '@{u}'],
          throwOnError: true,
          workingDirectory: workingDirectory,
      );
      revision = result.stdout.trim();
    } on Exception catch (e) {
      final String errorString = e.toString();
      if (errorString.contains('fatal: HEAD does not point to a branch')) {
        throwToolExit(
          'Unable to upgrade Flutter: Your Flutter checkout is currently not '
          'on a release branch.\n'
          'Use "flutter channel" to switch to an official channel, and retry. '
          'Alternatively, re-install Flutter by going to $_flutterInstallDocs.'
        );
      } else if (errorString.contains('fatal: no upstream configured for branch')) {
        throwToolExit(
          'Unable to upgrade Flutter: The current Flutter branch/channel is '
          'not tracking any remote repository.\n'
          'Re-install Flutter by going to $_flutterInstallDocs.'
        );
      } else {
        throwToolExit(errorString);
      }
    }
    verifyStandardRemote(localVersion);
    return FlutterVersion(workingDirectory: workingDirectory, frameworkRevision: revision);
  }

  /// Attempts a hard reset to the given revision.
  ///
  /// This is a reset instead of fast forward because if we are on a release
  /// branch with cherry picks, there may not be a direct fast-forward route
  /// to the next release.
  Future<void> attemptReset(String newRevision) async {
    try {
      await globals.processUtils.run(
        <String>['git', 'reset', '--hard', newRevision],
        throwOnError: true,
        workingDirectory: workingDirectory,
      );
    } on ProcessException catch (e) {
      throwToolExit(e.message, exitCode: e.errorCode);
    }
  }

  /// Update the engine repository and precache all artifacts.
  ///
  /// Check for and download any engine and pkg/ updates. We run the 'flutter'
  /// shell script re-entrantly here so that it will download the updated
  /// Dart and so forth if necessary.
  Future<void> precacheArtifacts() async {
    globals.printStatus('');
    globals.printStatus('Upgrading engine...');
    final int code = await globals.processUtils.stream(
      <String>[
        globals.fs.path.join('bin', 'flutter'), '--no-color', '--no-version-check', 'precache',
      ],
      workingDirectory: workingDirectory,
      allowReentrantFlutter: true,
      environment: Map<String, String>.of(globals.platform.environment),
    );
    if (code != 0) {
      throwToolExit(null, exitCode: code);
    }
  }

  /// Update the user's packages.
  Future<void> updatePackages(FlutterVersion flutterVersion) async {
    globals.printStatus('');
    globals.printStatus(flutterVersion.toString());
    final String? projectRoot = findProjectRoot(globals.fs);
    if (projectRoot != null) {
      globals.printStatus('');
      await pub.get(
        context: PubContext.pubUpgrade,
        directory: projectRoot,
        upgrade: true,
      );
    }
  }

  /// Run flutter doctor in case requirements have changed.
  Future<void> runDoctor() async {
    globals.printStatus('');
    globals.printStatus('Running flutter doctor...');
    await globals.processUtils.stream(
      <String>[
        globals.fs.path.join('bin', 'flutter'), '--no-version-check', 'doctor',
      ],
      workingDirectory: workingDirectory,
      allowReentrantFlutter: true,
    );
  }
}
